Chemistry MCQ thread...

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sakibfaiyaz

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MHHaider707 said:
Yeah, there should be a choice of 107*...

wat abt Q. 9 and 38??
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Ok I guess 9 is common sense...C and D wont be the answer (acids and ketones are not used as fuels)...
and i guess we know it from bio that a substance which is richer in Carbon-hydrogen bonds has a greater calorific value(its a fact so you can learn it).so the answer should be B
 
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xHazeMx

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check the bond energies of each compound. the greatest bond energies will release the greatest energy
 
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hassam

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all 3....that is A....ITS SIMPLE....2nd one is a characteristic acid-base reaction....and 3rd one a characteristic reaction of ammonium salts with alkalis...
talking abt 1st reaction....well CO2 is present in soil just like oxygen is found....so CO2....AN ACIDIC oxide...will again undergo acid base reaction
 
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xHazeMx

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hassam said:
all 3....that is A....ITS SIMPLE....2nd one is a characteristic acid-base reaction....and 3rd one a characteristic reaction of ammonium salts with alkalis...
talking abt 1st reaction....well CO2 is present in soil just like oxygen is found....so CO2....AN ACIDIC oxide...will again undergo acid base reaction
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just had a confusion about 1. thanks
 
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hassam

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14 Which of the following is the strongest reducing agent?
A Ba B Ba2+ C Mg D Mg2+
 
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Anonymousx3

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xHazeMx said:
why 2 is wrong ?
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I was wondering the same thing.
This is what it says in the ER:

"The most surprising response came in Q40, in which candidates were asked to identify those products of the hydrolysis of methyl butanoate, CH3CH2CH2CO2CH3, with NaOH (aq) that would be in a subsequent distillate. Whereas 80% correctly identified CH3OH, 70% thought that the salt, CH3CH2CH2CO2Na, would have distilled over."

What I gathered from that is, CH3CH2CH2CO2Na will not be present in the distillate.
 
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xHazeMx

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Anonymousx3 said:
xHazeMx said:
why 2 is wrong ?
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I was wondering the same thing.
This is what it says in the ER:

"The most surprising response came in Q40, in which candidates were asked to identify those products of the hydrolysis of methyl butanoate, CH3CH2CH2CO2CH3, with NaOH (aq) that would be in a subsequent distillate. Whereas 80% correctly identified CH3OH, 70% thought that the salt, CH3CH2CH2CO2Na, would have distilled over."

What I gathered from that is, CH3CH2CH2CO2Na will not be present in the distillate.
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alright then, a new info to add to our brains
 
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Abdulrab

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use of data booklet is relevant to this question !
What mass of solid residue can be obtained from the thermal decomposition of 4.1 g of anhydrous calcium nitrate ?
A. 0.7g
B 1.00g
C 1.40g
D 2.25g

i am getting C !! but it is not correct !! please give the answer with full working ! thnx
 
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hassam

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ya that was A barium..cos reducing agent has to loose e- and the most effective reducing agent wud be one with lowest I.E
 
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Zishi

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Abdulrab said:
use of data booklet is relevant to this question !
What mass of solid residue can be obtained from the thermal decomposition of 4.1 g of anhydrous calcium nitrate ?
A. 0.7g
B 1.00g
C 1.40g
D 2.25g

i am getting C !! but it is not correct !! please give the answer with full working ! thnx
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The answer has to be C. Does mark scheme say that C is wrong?
 
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